In Reply.—Dr Foulon and colleagues have made the important observation that persons who acquire measles in the hospital are more likely to develop serious complications of the disease than those who acquire measles in other settings. We have previously advised that transmission of measles in medical settings is of particular concern because of possible spread to those with a higher risk of complications.1 The age groups that, according to our data, are more likely to acquire measles in medical settings—infants and young adults—are also the age groups at higher risk of complications.2 In addition, those acquiring measles in medical facilities may be at greater risk of complications because of other, underlying illnesses.Data on complications among all 241 medical setting cases included in our report are not available. However, such data are available for an outbreak in 1983 in Kern County, California, in which transmission in medical